But it appears to have activity against Naegleria fowleri, which causes primary amebic meningoencephalitis, as well as granulomatous amebic encephalitis caused by Balamuthia mandrillaris and Acanthamoeba species, the agency said.

The announcement comes as physicians in Florida and Arkansas are treating two children with primary amebic meningoencephalitis -- the so-called brain-eating disease -- caused by N. fowleri.

The CDC announcement said that miltefosine has not led to successful therapy in cases of N. fowleri infection because it has been hard to import the drug in time to treat a fulminant case.

But there is some evidence from a small number of cases that the drug "does offer a survival advantage" for patients with infections caused by B. mandrillaris and Acanthamoeba species, the agency announcement said.

Meanwhile, the two children, both 12, remain in the hospital after infection with N. fowleri.

In late July, Kali Hardig of Arkansas was diagnosed with primary amebic meningoencephalitis after swimming in a sand-bottom lake at a water park in Little Rock.

Zachary Reyna, of LaBelle, Fla., apparently contracted an N. fowleri infection after kneeboarding in a ditch near his home and is now in intensive care at Miami Children's Hospital.

On a Facebook page, his father said antibiotics have apparently cleared the infection, but the child has had extensive brain damage and "the battle is not over."

N. fowleri invades the central nervous system through the cribriform plate and can be found in the subarachnoid and perivascular spaces. The subsequent inflammation progresses rapidly to the cerebral hemispheres, brain stem, posterior fossa, and spinal cord.

The ameba is commonly found in warm freshwater and soil, and patients usually get infected when the pathogen enters the nose while swimming or playing in water.

Physicians who have a suspected case of infection by a free-living ameba can call the CDC to consult with an expert. The agency added that gastrointestinal symptoms are the most commonly reported adverse effects of miltefosine and it is generally well-tolerated.

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